FC is the primary interconnect used for networked storage. Ethernet is the primary interconnect used for Local Area Networks (LANs). Both FC and Ethernet have previously been viewed as separate parallel protocols and complete solutions for different purposes. Furthermore, because Ethernet is known to be more unreliable than FC (Ethernet devices discard packets under certain conditions such as congestion), and FC provides for the reliable transport of frames, the two protocols have historically been viewed as incompatible solutions.
The historically separate and parallel nature of FC and Ethernet is illustrated in FIG. 1. FIG. 1 illustrates a conventional blade server chassis 100, which includes multiple blades 102, each blade having separate mezzanine cards 104 for separate FC and Ethernet Input/Output (I/O) controllers. The FC and Ethernet I/O controllers within each blade 102 are coupled to separate FC and Ethernet switches 106 and 108 over a backplane 110 that supports both FC and Ethernet. The Ethernet switch 108 receives data from all blades 102 and switches it to the correct destination via an external Ethernet network 112. The FC switch 106 receives storage traffic from all blades 102 and switches it to the correct destination via an external FC network 114.
More recently, however, efforts have been made to combine the FC and Ethernet protocols. For example, FC over Transmission Control Protocol/Internet Protocol (TCP/IP) (FCIP), (described in Request For Comments (RFC) 3643 and RFC3821, available at www.ietf.org), and internet FC Protocol (iFCP) (described in RFC4172), provide a method for transporting FC frames over TCP/IP/Ethernet. However, FCIP is fundamentally different from FCOE in that FCIP is a point-to-point protocol that does not route packets—all packets sent out at the transmitting end are received at the receiving end. iFCP uses TCP/IP as a transport. FCIP and iFCP also allow scaling to Wide Area Networks (WANs) and to the global Internet. However as a result of these extended capabilities, these protocols (FCIP and iFCP) are complex, expensive to implement, and have relatively low performance.
Accordingly, there is a need to layer FC over Ethernet is a manner that is less complex, more inexpensive and yet higher performing than FCIP or iFCP. In addition, it is desirable for this solution to be able to take advantage of the prevalence of legacy Ethernet switching devices and legacy FC software drivers, and allow a single physical adapter and a single wire to handle both Ethernet and storage traffic while sharing part of the switching infrastructure. There is also a need to take advantage of the wide availability of low cost Ethernet switching Application Specific Integrated Circuits (ASICs) and boxes to allow development of low cost FC switches and fabrics when FC is layered over Ethernet. Furthermore, given that 10 Gigabit (10 G) FC is not yet deployed in any significant volume, there is a need to develop FC over 10 G Ethernet (10 GbE) as a standard way of implementing FC at a 10 Gigabit data rate.